The present application relates to tourniquets, and particularly to emergency tourniquets intended for rapid application to a patient's limb, such as a severely injured leg or arm, to minimize or stop blood loss.
Most modern emergency tourniquets are applied by using the following three similar steps: 1) Placement: A tourniquet in the form of a loop is placed in the correct position around a wounded extremity, proximal to the injury sustained by an artery or other blood vessel. The tourniquet can either be fitted as a pre-existing closed loop, or a linear strap may be placed around the limb and then formed into a closed loop. Converting from a linear strap to closed loop is most commonly achieved by routing the strap through a buckle, or by the use of one of many other mechanisms including but not limited to a quick-release buckle already in place on the strap, or a hook-and-bar fastening arrangement.
2) Gross Circumference adjustment: A strap encircling a limb is manually pulled (usually through a buckle) to tighten the loop snugly around the extremity, removing all slack and, preferably, beginning to constrict the affected limb.
3) Fine Circumference adjustment: A mechanism is used to further tighten the loop to the point where blood flow is restricted or occluded. This mechanism is most commonly in the form of Spanish windlass, as in the CAT and SOFT-T tourniquets shown in U.S. Pat. No. 7,842,067 or 7,892,253 or may be one of many other mechanisms including but not limited to a ratchet as shown in U.S. Pat. No. 7,947,061, a string-and-pulley system, or a pneumatic system.
Three common shortfalls of available emergency tourniquets are:
1) Too much slack remains in the loop after Gross Circumference adjustment, leading to ineffectiveness of the Fine Circumference adjustment mechanism. This can result in slower application times, increased initial blood loss, or complete ineffectiveness.
2) The securement devices associated with the Gross Circumference adjustment mechanism may accidently loosen, fail, or be released after control of a hemorrhage is achieved, resulting in resumed or continued bleeding. This may be exacerbated by the fact that the Fine Circumference adjustment places an increasing force on the Gross Circumferential fastener, making the securement device more prone to failure.
3) The user is confused as to whether two tourniquets are necessary. Currently large thighs often require two tourniquets. However, the operator does not know whether a first tourniquet has too much slack in it or whether it is functioning as intended. As a result, the operator is not sure whether to remove and reapply the first one or put on a second.